Method for recovering ash from waste incineration

a technology of waste incineration and ash, which is applied in the direction of solid waste management, amphoteric ion exchangers, chemical/physical processes, etc., can solve the problems of insufficient sewage sludge purification process, significant increase in waste mass, and inability to add, so as to improve the efficiency of extraction of different elements, reduce the number of steps, and optimize the effect of steps

Active Publication Date: 2016-10-27
ECOPHOS
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Benefits of technology

[0017]Preferably, the said leaching liquor containing phosphate ions in solution is a phosphoric acid solution, with greater preference given to an aqueous solution of phosphoric acid. The use of a leaching liquor containing phosphate ions, preferably an aqueous solution of phosphoric acid, allows improving the effectiveness of the extraction of the different elements (especially phosphorous, calcium, magnesium, aluminium or iron) present in the ash, and thereby reducing the number of steps to be implemented in the process. Preferably, the leaching liquor does not contain any acid in addition to the phosphoric acid. In fact, the presence of another acid will result in the production of other soluble or insoluble salts in the water. The removal of these salts, and their separation from the phosphate salts, will require additional liquid-liquid, chemical precipitation or mechanical separation extraction steps. Thus, the ...

Problems solved by technology

The recovery of these types of waste may be complex, depending on their composition.
These processes therefore resulted in a significant increase in the mass of the waste, without adding to the value of their constituent elements, which are simply trapped i...

Method used

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  • Method for recovering ash from waste incineration
  • Method for recovering ash from waste incineration

Examples

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example 1

[0064]A leaching liquor is prepared, containing a phosphoric acid solution at 20.7% by weight of phosphate ions, from 481.1 g of a phosphoric acid solution at 85% by weight of H3PO4 and 1510.1 g of water. In a digestion reactor, 100 g of ash originating from the incineration of sludge from water purification plants is brought into contact with the phosphoric acid solution at 20.7% by weight of phosphate ions, as prepared above. The ash contains 36.2% of phosphorous (expressed in percentage % by weight in the form of PO4). The ash is digested for 30 minutes at 60° C. The reaction mix is filtered on a filter press. The filtrate is purified by applying 6 cation-exchange resins (Lewatit® S2568H-Lanxess) arranged in series. The aqueous solution of phosphoric acid recovered at the output of the sixth cation-exchange resin contains 98% of the phosphates initially present in the digestion reactor, i.e. of the phosphates initially present in the ash and in the leaching liquor. This phosphori...

example 2

[0066]Example 1 was reproduced using phosphoric acid solutions of different concentrations for digesting the ash. Four phosphoric acid solutions, respectively at 9.9% by weight of phosphate ions, 13.8% by weight of phosphate ions, 27.6% by weight of phosphate ions, and 34.5% by weight of phosphate ions, were prepared using a phosphoric acid solution at 85% by weight of H3PO4.

TABLE 2results of the digestion of the ash by phosphoric acid solutionsof different concentrationsweight % inweight % inphosphate ions inphosphate ions inEfficiencyExampleAsh (g)the leaching liquorthe filtrate(%)2A1009.911.1902B10013.815.495.52C10020.722.2982D10027.629.0992E10034.536.698

[0067]As shown by the results summarised in table 2, the phosphate content in the solution obtained after filtration (after step b) of this method) is greater than the phosphate content of the leaching liquor. The phosphorous present in the ash has been extracted and recovered in the form of a phosphoric acid solution. The effici...

example 3

[0068]Ash (100g) mainly containing 18.1% by weight of silicon, 8.7% by weight of aluminium, 15.7% by weight of calcium, 2.3% of iron, 1.5% by weight of magnesium, was treated with 1992 g of a phosphoric acid solution (20.7% by weight of phosphate ions) at 60° C. for 45 minutes. The ash contained less than 1% by weight of phosphorous (expressed in % by weight of PO4). The reaction medium is filtered by a filter press. The liquid phase is purified by the application of 5 ion-exchange resins placed in series (Lewatit® S2568H-Lanxess). A phosphoric acid solution with low contents of metal ions is recovered after this purification. The ion-exchange resins were regenerated with a hydrochloric acid solution at 5% and five aqueous solutions were recovered. The extraction efficiencies for aluminium, calcium, magnesium and iron were respectively 95%, 98%, 98% and 81%.

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Abstract

Methods treat ash from waste incineration, wherein the methods at least comprise: a) the digestion of the ash by a leaching liquor containing phosphate ions in solution such as to form a first solid phase comprising impurities and a first liquid phase comprising phosphate ions; and b) the separation of said first liquid phase comprising phosphate ions from said first solid phase. Step a) is carried out for a duration of less than one hour or at a temperature of more than 40° C.

Description

[0001]This application is a 371 application of PCT / EP2014 / 078736 filed Dec. 19, 2014, which claims foreign priority benefit under 35 U.S.C. 119 of European Application No. EP 13199070.7 filed Dec. 20, 2013.TECHNICAL FIELD[0002]This invention concerns the recovery of ash from waste incineration. In particular, this invention concerns the recovery of ash from the incineration of sludge from waste treatment plants, bones, manure or household waste.TECHNOLOGICAL BACKGROUND OF THE INVENTION[0003]Given the increasingly severe environmental and ecological constraints, the recovery of waste or residues, irrespective of their origin, has become all the more pertinent. Waste is generally incinerated to form two types of residues: solid non-combustible materials, called clinker or slag, containing high concentrations of pollutants such as heavy metals, which may be released when exposed to water; and residues from the smoke treatment, which are made up of ash from dust removal and smoke detoxi...

Claims

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Application Information

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IPC IPC(8): C22B7/02F23J1/00B01D15/36C05B17/00B09B3/00B01D11/02
CPCC22B7/02B09B3/0016B01D11/0288B01D15/361F23J2900/01007F23J1/00B09B2220/06B01D2011/005C05B17/00B09B3/00B09B5/00C05B11/10C05F1/005C05F3/00C05F7/00Y02P20/145Y02A40/20Y02P10/20B09B2101/30B09B3/80B09B3/40Y02W30/91
Inventor TAKHIM, MOHAMED
Owner ECOPHOS
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